Gypsum wallboard,wallboard construction method and wall structure



Sept. 30, 1969 D. A. WINKOWSKI 3,469,361

GYPSUM WALLBOARD, I WALLBOARD CONSTRUCTION METHOD AND WALL STRUCTUREFiled Feb. 9; 1968 I8 50 34 32 as I8 2o 20 I8 ze Fig. I

mvENToR. Figj BY Damel A.Wmkowsk| ATTORNEY United States Patent US. Cl.52-416 6 Claims ABSTRACT OF THE DISCLOSURE A method of constructing agypsum board wall and the improved wall, wherein the paper-coveredgypsum board is formed of a uniform cross section throughout its lengthincluding a uniformly thick center portion, and two opposed tapered,beveled edges. Application includes afiixing a pair of boards withtapered, beveled edges substantially abutting, followed by applying acoat of joint compound over substantially the full extent of the taper,thoroughly filling the bevel groove and embedding a narrow, thinreinforcing tape in this first coat of joint compound. Two additionalcoats of joint compound are applied over the respective dried priorcoat, forming a final joint compound dried surface substantially flushwith the surface of the center portion.

Background of the invention The present invention relates to gypsumwallboard anc particularly wallboard intended for use with a jointconcealing system to form what is commonly known as drywallconstruction.

Wallboard for drywall construction has for many years included anessentially square edge with the exception of a slight taper in the edgeportion thickness, which, for example, with a nominal /2-inch boardinvolved a /2inch thickness from the center to about 3 inches from theedge, the thickness then tapering to about .44 inch at the edge.

Another form of board which has been used to some extent is a bevelededge board, having essentially a uniform thickness throughout and anedge formation which is a square edge except for the bevel at one cornerof the edge. Thus the edge includes a fiat portion which isperpendicular to the plane of the faces of the board and a second flatportion which forms an angle of about 135 with the perpendicular fiatportion and also with an adjacent face of the board. Beveled edge boardwas not intended for use with a joint concealing system and, to thecontrary, the bevel was provided to make it possible to use wallboardswithout a joint concealing system. Two square edged boards mountedabutting each other Without a bevel and without a joint concealingsystem are not as aesthetically satisfactory as two abutting bevelededge boards with the joint exposed.

A prior problem with the common tapered edge board with a jointconcealing system covering the joints has been what is referred tocommonly as ridging and beading. This ridging and heading involves aphysical change in the joint concealing system subsequent to itsapplication over a joint and drying. This physical change is generally aformation of a slightly raised ridge or head immediately over thelocation of the joint and this may 3,469,361 Patented Sept. 30, 1969 notbecome visible for several days, or even months, after the wallconstruction is complete.

On more than one occasion it has been proposed to minimize this ridgingand heading by using a wallboard having the combination of a taperededge for the reception of a joint concealing system with the taperterminating in a quarter round which extends to or nearly to the boardedge back corner. The radius of such quarter rounds varied from aboutone-half the board thickness to about one and one-half times the boardthickness, such variation being the result of an inability to controlsuch an edge formation with available equipment.

As a result of the inability to control the quarterround size, widelyvarying sized grooves were formed by the abutting edges of such boards.It was found that the use of these boards did minimize ridging andheading, apparently as a result of the joint compound getting betweenthe board edges, drying or setting, and unitizing the two boards into amonolithic structure. However, when such quarter-round type edges havinga radius of about one to one and one-half times the board thickness wereused, the groove formed by two boards was of such size that an extrastep is required of filling the groove with a first application of jointcompound which must dry or set prior to applying the tape embeddingcoating of joint compound, or otherwise a reverse head, or groove,results in the finished wall. The inconvenience and labor cost of anextra step of filling the joint groove, and waiting for this filling todry or set, substantially offsets the advantage of avoiding ridging andbeading.

The quarter round type edges having a radius of one to one and one-halftimes board thickness also suffer from the fact that, when positioningabutting edges, the boards tend to overlap one another. Also theynecessitate the use of special, non-standard type of T-square, with anextra thick head portion of the T. Still further, it has been found thatsuch boards are very uncomfortable to the bare hand when one is carryingthe board by the side edge, as is common, because of the sharper cornerformed at the board edge. This relatively sharp corner is alsorelatively more susceptible to damage, than other board edges.

Summary of invention This invention relates to a wallboard for use indrywall construction, wherein ridging and heading are avoided withsubstantially no extra inconvenience or cost, the novel wallboardconsisting of a generally flat center portion and two side edge portionseach edge portion including a board edge taper and a tapered frontcorner edge.

Drawings FIG. 1 is a cross-sectional perspective plan view of acompleted drywall structure embodying the present invention.

FIG. 2 is a perspective view of the end of a gypsum wallboard embodyingthe present invention.

FIG. 3 is an end view of one tapered beveled edge of the wallboard ofFIG. 2.

FIG. 4 is an enlarged end view of the beveled edge portion of thewallboard of FIG. 2. A second wallboard edge portion is shown inphantom, in adjacent relation as in the structure of FIG. 1.

FIG. 5 is an even further enlarged view of paper cover sheet of thebeveled edge portion of FIG. 4, prior to manufacture of the gypsumwallboard.

Referring to FIG. 1, there is shown a plan view of a cross section of ahollow vertical wall including vertical sheet metal elongate studs 12mounted in spaced parallel relation. Novel tapered and beveled edgegypsum wallboards 14 are screw attached to studs 12. Normally, four footwide wallboards are attached, with their length extending vertically, tostuds 12 which are mounted on two foot spacing, with the wallboardjoints 16 of the respective two sides of the wall 10 located overalternate studs. Thus each stud 12 has screw attached to it the centerportion 18 of a wallboard on one side of the stud 12 and two adjacentedge portions 20, 20, of two adjacent wallboards 14, 14, on the otherside of stud 12. The screws 22 extend through the wallboard andpenetrate and grasp one of sheet metal flanges 24 of the stud 12. Thescrew heads 26 of the screws 22 disposed at the center of a wallboardare concealed by a thin small patch 28 of joint compound, tapered to asubstantially flush indistinguishable condition relative to thesurrounding surface of wallboard 14.

The joints 16 and the screw heads 26 of the screws 22 disposed at theedge portions 20 are concealed by a joint treatmentv system 30 whchconsists of a combination of a joint reinforcing paper tape 32 and jointcompound 34 which functions both to adhere the tape 32 to the wallboard14 and to conceal the tape 32. The two edge portions 20, of the abuttingwallboards, are each formed with a tapered face 36, the two taperedfaces forming a recess 38 whereby the joint treatment system may beapplied in complementary tapered form producing a surface flush with thesurface of the wallboard center portion 18.

In accordance with the invention, the edge portions 20 also include abevel 40 adjacent the tapered face 36, and a perpendicular portion 42,adjacent and perpendicular to the back face 44 of the wallboard 14. Inthe preferred form of the invention, a wallboard of any given nominalthickness, the thickness throughout the center portion, has an edgeportion 20 extending from the board edge 46 inward a distance at leastone inch, preferably about 2 to 3 inches, for example, 2 inches, withthe edge portion thickness tapering from nominal thickness at theinnermost part of the edge portion to about .060 inch less than nominalat the outermost part of the tapered face. Two abutting boards thuswould form a recess five inches wide and .060 inch deep at the center,for the joint concealing system 30. The bevel 40 forms an angle on ofbetween 95 and 125 with the tapered face 36, preferably about 100 to120, for example 110. Perpendicular portion 42 has a width between aboutonequarter and three-quarters of the board nominal thickness andpreferably about one-half nominal thickness. For example, a one-halfinch nominal thickness board tapers to 0.44 inch and has a bevel about0.18 inch wide and a perpendicular portion about 0.26 inch wide.

Wallboard 14 is formed of a gypsum core 48 and a paper cover 50. Priorto the manufacture of the wallboard 14, the inner surface of the papercover is scored along parallel lines disposed for forming the fold 52 atthe edge of bevel 40 adjoining the tapered face 36, the fold 54 at theopposite edge of bevel 40, and fold 56 at the back corner ofperpendicular portion 42. The scoring i 58 of the inner face consistspreferably of the removal of a layer of the paper about .05 inch wide,and about .005 inch to .010 inch thick with the usual gypsum paper ofabout .020 inch thickness. This scoring is carefully controlled, as by aplurality of .05 inch wide, rotating abrapaper reinforcing tape 32 isembedded therein. This embedding layer of joint compound also extendsinto and fills the opening between the adjacent bevels 40, 40 of the twoabutting wallboards. In accordance with the abovedefined size of theangle a, it will be seen in FIG. 4 that an angle a, formed in theopening between two adjacent bevels 40, 40, is between about 10 and 70,preferably about 20 to 60, for example about 40. The tape 32 is embeddedin the embedding layer immediately and the embedding layer of jointcompound is allowed to set and dry, bonding the tape to the board. Twoadditional progressively wider coats of joint compound are successivelyapplied and allowed to separately set and dry, the last coat beingpreferably about equal in width to the recess 38 width and thus beingsubstantially flush with the surface of center portion 18.

The joint compound, at least for the first coat for embedding tape andfilling the opening formed by the bevels, is a low shrinkage, fastsetting type joint compound, setting in about to 110 minutes to ahardness such that a quarter pound Gilmore needle is substantiallyuniformly supported therethroughout, which method for establishingsetting time is well known in the art.

The formation of the bevel 40, using an internally scored paper, issusceptible of control in present day wallboard manufacturing processesand techniques, whereby the size of the opening formed between a pair ofbevels is sufficiently uniform to permit combining of the filling ofthis opening and the step of embedding the tape. Accordingly, a unitizedstructure of two adjacent wallboards may be formed without anysubstantial increase in cost of application, providing a markedimprovement in the art of drywall construction with minimized ridgingand beading.

Having completed a detailed disclosure of the preferred embodiments ofmy invention, so that others may practice the same, I contemplate thatvariations may be made without departing from the essence of theinvention or the scope of the appended claims.

I claim:

1. Gypsum wallboard comprising a paper cover and a set gypsum core, saidwallboard including a center portion of substantially uniform thicknessforming a major area of said board and two opposite side edge portions,each said edge portion being tapered on the face side of the board fromthe thickness of said center portion at the innermost part of said edgeportion to about .010 inch to .100 inch thinner at the outermost part ofsaid tapered portion, a bevel extending from said outermost part of saidtapered portion to the outer edge of said wallboard, a perpendicularportion disposed substantially perpendicular to the plane of the face ofsaid center portion, and a wallboard back face, said wallboard back faceforming substantially a right angle with said perpendicular portion,said bevel forming an angle of between and about 125 with said taperedportion, the ratio of the width of said perpendicular portion to thewidth of said bevel being from about 1:3 to about 3:1.

2. The wallboard of claim 1 wherein said bevel and said tapered faceform an angle of about to 3. The wallboard of claim 1 wherein saidperpendicular portion is wider than said bevel width by a ratio o fabout 1 /2:1.

4. The wallboard of claim 1 wherein said paper is scored on the innersurface at each edge of said bevels and perpendicular portions withgrooves of about .005 to .010 inch depth andabout .05 inch wide.

5. A wall structure comprising a pair of wallboards as defined in claim1 having respective side edges substantially abutting, whereby saidadjacent bevels form a V-shaped opening of from about 10 to about 70 andsaid adjacent tapered portions forma relatively wide,

shallow recess, said recess and said V-shaped opening beingsubstantially filled, with a set and dried joint com- 5 pound and a,reinforcing tape embedded therein and 1,672,099 bridging said V-shapedopening. 2,850,404 6. A wall structure as in claim 5 wherein the ratio3,180,058 of the width of the perpendicular portion of said wallboardedges to the Width of said bevels is about 1 /2:1. 5 584 202 ReferencesCited UNITED STATES PATENTS 1,526,108 2/1925 Adams 52417 1,564,45512/1925 Stanbro 52362 10 1,638,280 8/1927 Utzman 52344 6/1928 Schumacher52361 9/1958 Dunlap 52417 4/1965 Tillisch et a1. 52417 FOREIGN PATENTS1/ 1947 Great Britain.

FRANK L. ABBOTT, Primary Examiner JAMES L. RIDGILL, JR., AssistantExaminer U.S. Cl. X.R.

